Field of the Invention
The present invention relates to a technique of displaying image data in an object information acquiring apparatus.
Description of the Related Art
Many proposals have been made for techniques to capture a tomographic image inside an object in a noninvasive way. One such technique is photoacoustic tomography (PAT) that acquires bio-function information using light and ultrasound.
Photoacoustic tomography is a technique that irradiates an object with pulsed light generated in a light source, receives and analyzes photoacoustic waves (typically ultrasonic waves) generated by the light that is absorbed in the object, and generates an image of the internal tissue. By detecting time-based changes of the received acoustic waves at a plurality of locations and mathematically analyzing and reconstructing the acquired signals, information related to optical characteristics, such as the absorption coefficient inside an object, can be visualized.
Near-infrared light can easily transmit through water which constitutes most of an organism, and is easily absorbed by hemoglobin in blood, therefore a vascular image can be acquired if near-infrared light is used for pulsed light. Furthermore, oxygen saturation in blood, which is function information, can be measured by comparing vascular images acquired by pulsed lights having different wavelengths. Since the oxygen saturation of blood around a malignant tumor should be lower than that of blood around a benign tumor, it is expected that knowing the oxygen saturation assists in distinguishing a benign from a malignant tumor.
A known technique related to this art is disclosed, for example, in the following document: “Noninvasive imaging of hemoglobin concentration and oxygenation in the rat brain using high-resolution photoacoustic tomography” by Xueding Wang et al, Journal of Biomedical Optics 11(2), 024015, March/April 2006)
“Noninvasive imaging of hemoglobin concentration and oxygenation in the rat brain using high-resolution photoacoustic tomography” document discloses a photoacoustic tomography apparatus that distinguishes a signal portion which is a portion where blood is assumed to exist and a background portion which is a portion other than the signal portion, based on a measured absorption coefficient inside the object, and creates and displays only the oxygen saturation distribution of the signal portion.